libgetopt++ is a C++ library to parse options that a program gets specified
from the command line. It has the following features:
* Minimal footprint in main.cc, and no header or source changes outside the
user of an option when the option is altered or a new option added.
* Multiple option sets can co-exist safely. The default option set is a
singleton, but additional static sets can be created and used.
* Easy to use: adding a new option is simply a case of adding a static
variable for the option, in the scope that the option needs to be visible.
* There are multiple concrete Option classes provided: Bool, String,
StringCollector.
* Extensible: simply create a new subclass of Option to implement a new
Option type, and use it in your program.